1. Field of the Invention
The present invention relates generally to facilitating release of powder contained in a receptacle. More specifically, the present invention relates to the administration of medication by a method and apparatus for facilitating inhalation of powder medicaments.
2. Related Art
In the medical field, it is often desirable to administer various forms of medication to patients. Well known methods of introducing medication into the human body include the oral ingestion of capsules and tablets, intravenous injection through hypodermic needles, and numerous others. In one method, certain medications may be inhaled into a patient""s respiratory tract and lungs through the nose or mouth. Certain of these medications, such as bronchodilators, corticosteroids, etc., for the treatment of asthma and other respiratory anomalies, may be aimed at the respiratory tract directly. Others are inhaled for purposes of systemic treatment, i.e. for treatment of any area of the body through absorption from the respiratory tract through the lung tissue, into the deep lungs, and into the bloodstream. Each of these medications comes in a variety of forms, including fluids, which are commonly administered as an aerosol vapor or mist, as well as solids. Inhalable solids typically take the form of fine, dry powders. Specialized devices, such as inhalers, are provided to assist the patient in directing these fine powder medications into the respiratory tract.
Various types of inhalers are known for the administration of dry powder medicaments. However, each of these inhalers suffers certain drawbacks. For example, U.S. Pat. No. 5,787,881 discloses an inhaler that is used with encapsulated dry powder medicaments. However, use of this device requires numerous steps and imposes a number of inconveniences on a user. For example, the medication capsules used with the device have an aperture formed therein prior to insertion into an opening in the inhaler. Therefore, there exists a danger that an amount of medication may be lost prior to or during insertion into the device. After insertion of the capsule, use of the device requires the additional step that a cover must be closed before the medication may be inhaled.
Inhalation devices configured for use with a capsule containing some type of medicament are shown in U.S. Pat. No. 4,069,819 to Valentini et al. (xe2x80x9cthe ""819 patentxe2x80x9d) and U.S. Pat. No. 4,995,385 to Valentini et al. (xe2x80x9cthe ""385 patentxe2x80x9d). The inhalation device described in the ""385 patent was developed to overcome the drawbacks of the device described in the ""819 patent. Particularly, in a large number of cases, the device described in the ""819 patent experienced irregular and incomplete emptying of the capsule, thereby resulting in difficulties in properly administering the medicament in the capsule. The inhalation device described in the ""385 patent attempts to overcome this deficiency by tapering the nebulization chamber toward the end surface that comprises the discharge holes. Thus, the nebulization chamber of the ""385 patent is not cylindrical, but rather frusto-conical in form in an attempt to achieve regular complete emptying of the nebulization chamber. However, further improvements in the design of inhalation devices are needed to achieve a higher emitted dose. As used herein, xe2x80x9cemitted dosexe2x80x9d refers to the percentage of the dose of powder medicament, contained in a receptacle in the inhalation device, that is emitted from the inhalation device. Moreover, improvements are needed to achieve higher emitted doses that are consistently reproducible, i.e., with low standard deviation. There is a particular need in the art for high, reproducible emitted doses at low flow rates, as well as for high dosage ranges.
Another drawback of the inhalation devices described in the ""819 and the ""385 patents is the piercing device that is used to puncture the capsule. Such conventional piercing devices are formed from circular stock, with the points created by pinching the stock at an angle, thereby creating a single sharp cutting edge. Drawbacks of such a design are that the point (which must puncture the capsule material) is often rounded, lessening its effectiveness as a piercing device. Moreover, burrs often form on the lower edge, which can stop the piercing device from retracting from the capsule, thereby causing a device failure. The holes formed by such a conventional piercing device are generally round, and do not have the appearance of being cut by a sharp edge. With such a conventional design, the capsule is often crushed, rather than punctured or pierced. If such a conventional piercing device is used with brittle capsule materials such as gelatin, pieces of capsule material of a size that can be inhaled are usually broken off from the capsule. Thus, conventional piercing devices are less than optimal, particularly for brittle capsule material.
Thus, there is a need in the art for an improved method and apparatus for inhalation of dry powder medicaments. What is needed is an inhaler that provides for a higher emitted dose that is consistently reproducible with low standard deviation. Such a need is particularly acute for low flow rates, and for high dosage ranges. There is a further need in the art for an improved means for puncturing the capsule containing the medicament. The present invention, the description of which is fully set forth below, solves the need in the art for such improved methods and apparatus.
The present invention relates to a method and apparatus for facilitating release of powder from a device. In one aspect of the invention, a device for emitting powder is provided. The device includes a first casing portion, and a second casing portion removably coupled to the first casing portion. A cylindrical chamber, defined by a straight wall of circular cross section, is coupled to the first casing portion. The chamber has a proximal end and a distal end. A ring is circumferentially coupled to an inner surface of the chamber. The ring is preferably disposed at approximately a midpoint of the chamber, or, alternatively, disposed adjacent the proximal end of the chamber. The second casing portion includes an emitter portion disposed at the proximal end of the chamber when the first and second casing portions are coupled together. The emitter portion defines at least one aperture configured to emit powder therethrough.
In another aspect of the present invention, the device is configured as an inhalation device for administering powder. In this aspect of the present invention, the emitter portion is configured as an inhalation portion so that powder is dispersed in the chamber and administered to a user through the inhalation portion. The inhalation portion may be configured as a mouth piece for inhalation through the mouth, or as a nose piece for inhalation through the nose.
In one aspect of the invention, the powder is contained in a receptacle that is disposed in the chamber. Upon puncturing the receptacle, powder is dispersed in the chamber and emitted or inhaled from the device.
In yet another aspect of the present invention, the device of the present invention includes means for puncturing the receptacle. The means for puncturing can be configured as a staple. Such a staple is preferably configured in a substantially U-shape, having two prongs. In one aspect of the present invention, each of the prongs has a square cross-section. In another aspect of the present invention, the substantially U-shaped staple includes a rounded portion and two prongs that define a non-planar inner edge and a non-planar outer edge of the staple, the staple being formed from a rectangular length having two end surfaces and four planar side surfaces that intersect to form four non-planar edges. The inner edge of the staple is configured to be one of the non-planar edges, and the outer edge of the staple is the non-planar edge that is opposite that non-planar edge. Each end surface is an angled diamond-shaped surface. In a preferred aspect, each end surface has a top point at an apex of the inner edge, and a bottom point at an apex of the outer edge, each top point forming a cutting point for one of the prongs.
In still a further aspect of the present invention, a method for dispensing powder by inhalation is provided. Such a method comprises
providing a powder inhalation device, the device comprising
a first casing portion,
a cylindrical chamber, defined by a straight wall of circular cross-section, coupled to said first casing portion, said chamber having a proximal end and a distal end and configured to receive a receptacle therein, said chamber comprising a ring circumferentially coupled to an inner surface of said chamber, and
a second casing portion removably coupled to said first casing portion, said second casing portion comprising an inhalation portion disposed at the proximal end of said chamber when said first and said second casing portions are coupled, said inhalation portion comprising a hemispheric region defining a plurality of apertures configured to emit powder therethrough;
puncturing the receptacle to disperse powder in said chamber; and
inhaling the powder through said inhalation portion.
In one aspect of the present invention, the inhaling step is carried out by inhaling the powder through a mouthpiece into a user""s mouth. Alternatively, the inhaling step may be carried out by inhaling the powder through a nose piece into a user""s nose.
Features and Advantages
One feature of the present invention is that it provides high emitted doses that are consistently reproducible over a range of flow rates and dosage quantity. Advantageously, the present invention improves the emitted dose at both low flow rates and high dose ranges. A particularly advantageous feature of the present invention is its ability to operate at low flow rates, such as would be associated with a child or a person with a respiratory disease.
One advantage of the present invention is that the preferred means for puncturing used in the device is less expensive to manufacture than conventional piercing devices. Moreover, the means for puncturing of the present invention advantageously provides improved puncturing performance since less force is needed to puncture the receptacles, and fewer failures result than with conventional piercing devices.
Another advantage of the preferred means for puncturing is an improvement to the flow rate independence of the inhaler. Consequently, the powdered medicament delivered to a patient will be independent of how fast the patient breathes, thereby ensuring that a consistent dose of medicament is delivered each time.
Another advantageous feature of the present invention is the accuracy of medicament dosage delivered thereby. Since only one dosage of medication is present in the inhaler during each use, the possibility of overdose is eliminated, and the medicament need not be metered prior to delivery. A patient may simply inhale all medicament present in the device.
Because the present invention operates only under the inhalative power of the patient, the inhaler carries the additional advantage that no accessory device, such as a compressed air cylinder or other propellant, needs to be used in conjunction with the present invention.
Another advantage of the present invention is that during inhalation, the medicament is subjected to mixing in the dispersion chamber. This helps to ensure that the medicament exiting the inhaler and entering the patient""s respiratory system is in the form of a fine dry powder, facilitating medicament deposition in the lungs. In addition, inhalation of finer powders is typically more comfortable for the patient.
Still another advantage of the present invention is that it can be used with individuals who cannot breathe hard, such as a child or an asthmatic, or individuals who are sleeping or in a coma.
Yet another advantage of the apparatus of the present invention is that it is reusable. To reuse, a patient removes the emptied receptacle, and replaces it with a fresh receptacle filled with the proper dose of medicament.